Push-pull optical fiber connectors are known, such as that disclosed by Umeki et al, Japanese Showa 60-218932. This connector includes an adapter equipped with an alignment sleeve and resilient catch pieces. The pieces are in cantilever form with protrusions and a claw attached to the tip of the form. The connector also includes a frame that contains an integrated ferrule and a through passageway from the rear to the front of the ferrule. The frame has protruding parts that are caught by claws of the resilient catch pieces of the adapter. A resilient inner tube shaped in the form of a round tube has an inside diameter almost equal to the outside diameter of the optical fiber cable and an outside diameter almost equal to the hole in the rear portion of the plug frame. A cord tube has a flexible part at its front end which, when inserted into the hole in the rear of the plug frame, is secured to the frame by the bending of the flexible part. The plug frame also has a finger grip mounted on its outside with raised parts. When the ferrule of the plug frame is inserted into or pulled from the alignment sleeve, the raised parts of the plug frame contact the protrusions of the cantilever form and push the resilient claws apart allowing the protrusions to pass. The plug frame may have a finger grip housing which is able to slide forward and backward with respect to the plug frame and, additionally, which has raised parts which release the catch of claws on the protruding parts of the plug frame when the finger grip housing is moved backward.
The present invention relates to a particular adapter for disconnect connection of an optical fiber of the push-pull coupling type of connector such as disclosed by Umeki et al, Japanese Showa 60-218932; Iwasa et al, Japanese Showa 62-26141; Kaihara et al, U.S. Pat. No. 4,762,389; and Myers et al, U.S. Pat. No. 4,872,736. Particularly, the invention relates to the adapter for the push-pull coupling type of connector as disclosed by Mulholland et al, U.S. patent application Ser. No. 491,755, filed Mar. 9, 1990, which disclosure is incorporated herein by reference.
One of the distinct advantages of push-pull connectors is their ease of connection to other connecting devices, particularly through the means of the adapter assemblies of Umeki et al. and Mulholland et al. It is the ability of these connectors to seat precisely, quickly and easily to the adapter assemblies, and without the need of crimping tools, adhesives or the like, that make these push-pull connectors particularly advantageous over other optical fiber connectors known in the art.
Sugita et al., in an article in the Journal of Light and Technology, Volume 7, No. 11, (November, 1989), pages 1689-1696, entitled "SC-Type Single Mode Optical Fiber Connectors", describes the coupling mechanism and coupling forces involved during the mating of push-pull type connectors and adapters. Noted is that it is essential that the SC connector provide easy insertion and removal operation, and further, that a strong coupling interrelationship be established between the plug and the adapter. Further, as the article points out, the most important point for satisfying these objectives is finding the optimum design for the adapter part identified in the article as the spring lever, which is the same piece as is described in various of the patents as the resilient catch piece Umeki et al., describes the resilient catch piece, provided in pairs on both sides of a support of the adapter, as terminating in protrusions and claws. Mulholland et al. describes the catch pieces as terminating in protrusions and lip structures. In either instance, whether described as a claw or a lip, the structure has a beveled surface which facilitates the fitting of the catch piece into a depression or slot of the connector during insertion of the connector into the adapter. During intermating of adapter and connector, the bevel of the protrusion supporting the lip contacts an upward slope of the front edge of the connector which opens the catch piece by pushing against the beveled surface causing the catch piece to rise and then to seat with snap-in connection to a connector slot. The present invention relates to an adapter assembly of improved design whereby the lip structures are characterized by at least three inwardly beveled surfaces leading from the lip edge of each structure forward toward the interconnection with the connector. The additional beveled surfaces provide an orienting feature for the longitudinal alignment of the connector face during intermating with the adapter.